Vortex flowmeter is mainly used for measuring the flow rate of medium fluid in industrial pipelines, such as gas, liquid, steam and other medium.Special phenomena and problems will appear in the process of measurement.The key problem of * is that the steam density value deviates too much from the design value, which brings significant measurement error to the measurement results. At present, the mature technology of density detection instrument has not been successfully applied, which brings certain difficulties to the steam flow measurement.

Description of vortex flow meter compensation:

1. One-time compensation implementation method

Firstly, the working parameters of steam -- temperature and pressure are determined. The flowmeter determines the density of steam in working state according to the working parameters, and takes this density as the density of steam in the process of future flow measurement for orifice calculation.In the work no longer to the actual change of steam compensation or correction, this is the so-called one-time calculation compensation method.

The accuracy of steam flow measurement can be guaranteed if the steam operating parameters are consistent with the set value at design time during operation.If the parameters deviate from the actual working conditions, or even deviate a lot, the deviation of the measurement results may be very large.

The one-time compensation method is used in the early stage of the development of automatic detection technology. The measurement results have large errors and can be used as a rough measurement.Such a design method is still used in the current widely popular flow throttling device design manual.

2. Implementation method of online density compensation

With the wide application of microelectronics technology in instrumentation.The calculation function, compensation and correction function, accumulation function, historical data storage function, digital filtering function, output function, digital communication function and so on can be easily realized.Therefore, on-line density compensation has become an essential basic function of steam meter and has been widely used.

1. Saturation vapor on-line density compensation.

The flowmeter can realize integrated temperature and pressure compensation, and there is a strict one-to-one correspondence between the temperature and pressure of saturated steam.The density of a saturated vapor may be a single function of its temperature or of its pressure.According to the temperature value or pressure value of saturated steam, the real-time density value can be obtained by means of table lookup or formula calculation (IFC1967 or IAPW-1997).

In flow measurement, the flowmeter can be realized by temperature compensation or pressure compensation.Choose the flowmeter with temperature compensation function.Turn on the temperature sensor of the flowmeter to detect the temperature of the measured steam in real time, so as to obtain the corresponding density value.

2. Online density compensation of superheated steam

Superheated steam is a special quality of steam obtained by reheating saturated steam.It breaks the strict one-to-one correspondence between temperature and pressure inherent in saturated steam.The flowmeter may treat the superheated steam as a single medium during flow measurement.The density of superheated steam is a composite function of its temperature and pressure.When ordering the flow meter, choose the temperature and pressure compensation type.In actual use, the temperature and pressure sensors are turned on to measure the steam temperature and pressure in real time, and the density value can be accurately calculated according to the superheated steam density table or density calculation formula.

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